Complex III: The coenzyme QÂ : cytochrome c-oxidoreductase, sometimes called the cytochrome bc 1 complex, and at other times complex III, is the third complex in the electron transport chain ( EC 1.10.2.2 ), playing a critical role in biochemical generation of ATP ( oxidative phosphorylation ). Complex III is a multisubunit transmembrane protein encoded by both the mitochondrial ( cytochrome b ) and the nuclear genomes (all other subunits). Complex III is present in the mitochondria of all animals and all aerobic eukaryotes and the inner membranes of most eubacteria.
[Source: Wikipedia]